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Re: overriding motherboard ROM with a peripheral card in a platinum iie

Subject: Re: overriding motherboard ROM with a peripheral card in a platinum iie
From: Linards Ticmanis <ticmanis@gmx.de>
Date: Fri, 21 Mar 2008 01:30:46 +0100
In-reply-to: <1ZBEj.15572$dq2.7012@trndny05>
Newsgroups: comp.sys.apple2
Organization: Arcor
References: <47980c91-66bd-40fc-aef1-38484caacfd2@u10g2000prn.googlegroups.com> <47E2E230.20400@willegal.net> <1ZBEj.15572$dq2.7012@trndny05>
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Mike Willegal wrote:

Rather than checking all 16 address bits for $CFFF, usually the invertedversion of I/O strobe is anded with (A8 & A9 & A10). This results in areset of the flip-flop with any address CFxx and the loss of 256 bytesof PROM space, but fewer chips are required to implement this.

And those 256 bytes can conveniently be used for the CnXX space, so thatyou need only one 2716 for the card.


--
Linards Ticmanis

References:
- overriding motherboard ROM with a peripheral card in a platinum iie
  - From: jonnosan <jonnosan@gmail.com>
- Re: overriding motherboard ROM with a peripheral card in a platinum iie
  - From: Mike Willegal <mike@willegal.net>
- Re: overriding motherboard ROM with a peripheral card in a platinum iie
  - From: Mike Willegal <mike@willegal.net>

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